docs: def tb2radiance(self, tb_, **kwargs):
          """Get the radiance from the Tb using the simple non-linear regression
          method. SI units of course!
          """
          # L = C1 * νc**3 / (exp (C2 νc / [αTb + β]) − 1)
          #
          # C1 = 2 * h * c**2 and C2 = hc/k
          #
          lut = kwargs.get('lut', None)
          normalized = kwargs.get('normalized', True)
  
          if lut is not None:
              raise NotImplementedError('Using a tb-radiance LUT is not yet supported')
          if not normalized:
              raise NotImplementedError('Deriving the band integrated radiance is not supported')
  
          c_1 = 2 * H_PLANCK * C_SPEED ** 2
          c_2 = H_PLANCK * C_SPEED / K_BOLTZMANN
  
          vc_ = SEVIRI[self.bandname][self.platform_name][0]
          # Multiply by 100 to get SI units!
          vc_ *= 100.0
          alpha = SEVIRI[self.bandname][self.platform_name][1]
          beta = SEVIRI[self.bandname][self.platform_name][2]
  
          radiance = c_1 * vc_ ** 3 / \
              (np.exp(c_2 * vc_ / (alpha * tb_ + beta)) - 1)
  
          unit = 'W/m^2 sr^-1 (m^-1)^-1'
          scale = 1.0
          return {'radiance': radiance,
                  'unit': unit,
                  'scale': scale}